The effect of co-trimoxazole on serum potassium concentration: safety evaluation of a randomized controlled trial

Potassium homeostasis - Physiology and pharmacology in a clinical context

Membrane voltage controls the function of excitable cells and is mainly a consequence of the ratio between the extra- and intracellular potassium concentration. Potassium homeostasis is safeguarded by balancing the extra-/intracellular distribution and systemic elimination of potassium to the dietary potassium intake. These processes adjust the plasma potassium concentration between 3.5 and 4.5 mmol/L. Several genetic and acquired diseases but also pharmacological interventions cause dyskalemias that are associated with increased morbidity and mortality. The thresholds at which serum K+ not only associates but also causes increased mortality are hotly debated. We discuss physiologic, pathophysiologic, and pharmacologic aspects of potassium regulation and provide informative case vignettes. Our aim is to help clinicians, epidemiologists, and pharmacologists to understand the complexity of the potassium homeostasis in health and disease and to initiate appropriate treatment strategies in dyskalemic patients.

Trimethoprim-associated hyperkalaemia: a systematic review and meta-analysis

INTRODUCTION

Trimethoprim is structurally similar to potassium-sparing diuretics and may induce hyperkalaemia. The prevalence and the factors that predispose to trimethoprim-associated hyperkalaemia have never been extensively addressed.

METHODS

A literature search with no date or language limits was carried out using the National Library of Medicine, Embase and Web of Science in March and repeated during August 2021. The principles underlying the Economic and Social Research Council guidance on the conduct of synthesis and the PRISMA guidelines were employed. For the analysis, we retained reports including ≥10 subjects on treatment with trimethoprim, which addressed the possible occurrence of hyperkalaemia.

RESULTS

Eighteen reports were retained for the final analysis. The pooled prevalence of potassium value >5.0 mmol/L, >5.5 mmol/L and >6.0 mmol/L or symptomatic, was, respectively, 22%, 10% and 0.2%. The analysis disclosed that the risk of trimethoprim-associated hyperkalaemia is dose-related and enhanced by drugs with known hyperkalaemic potential including potassium-sparing diuretics, renin-angiotensin-aldosterone system inhibitors, β-blockers and non-steroidal anti-inflammatory agents. Poor kidney function also increased the tendency towards hyperkalaemia. The time to onset of hyperkalaemia was generally 1 week or less after starting trimethoprim.

CONCLUSIONS

The present analysis documents the hyperkalaemic potential of trimethoprim, a widely prescribed drug that was introduced more than 50 years ago. Clinicians must recognize patients at risk of trimethoprim-associated hyperkalaemia.

Population kinetic-pharmacodynamic analysis of serum potassium in patients receiving sulfamethoxazole/trimethoprim

Since trimethoprim (TMP) dose-dependently inhibits the excretion of potassium, a population kinetic-pharmacodynamic analysis was performed to establish an adequate dosing schedule and characterize factors of hyperkalaemia. Dataset was constructed using a retrospective observational cohort of hospitalized patients (>18 years) with oral sulfamethoxazole/trimethoprim formulation. The model integrated a kinetic model for TMP, a urinary TMP concentration-response curve, and a kinetic model for serum potassium using an indirect response model. The model was a function of body weight, renal function, serum potassium levels, and TMP dosing schedule. We evaluated covariates by the stepwise forward and backward selection methods. The Monte Carlo simulation determined the probability of hyperkalaemia (>5.5 meq/L or >6.0 meq/L) according to the dosing schedule, renal function, and covariates. This study included 317 patients (age 62 [42-72] years) with 4359 serum potassium levels. The significant covariate was non-steroidal anti-inflammatory drugs (NSAIDs), with a 72.3% reduction in 50% inhibitory concentration. Monte Carlo simulation revealed that high-dose TMP (400 mg thrice daily) co-administered with NSAIDs led to mild hyperkalaemia (>10%) and severe hyperkalaemia (approximately 5%), regardless of renal function. In conclusion, clinicians should pay attention to hyperkalaemia with TMP high-dose and co-administered NSAIDs.

Effect of high-dose sulfamethoxazole/trimethoprim and glucocorticoid use on hyperkalemic event: A retrospective observational study

INTRODUCTION

Sulfamethoxazole/trimethoprim causes hyperkalemia; however, the effect of sulfamethoxazole/trimethoprim dose and co-administered glucocorticoids on hyperkalemia has not been clarified.

METHODS

This single-center, retrospective, observational cohort, chart review study involving patients (>20 years) who were treated with sulfamethoxazole/trimethoprim was conducted at Tokyo Women's Medical University, Medical Center East from June 2015 to May 2019. Multivariate Cox proportional hazard model was used to identify risk factors for hyperkalemia (serum potassium level > 5.5 mEq/L). Additionally, Kaplan-Meier curve analyzed the cumulative incidence of hyperkalemia focusing on sulfamethoxazole/trimethoprim dose and concomitant use of glucocorticoids with mineralocorticoid activity.

RESULTS

Among 333 patients, 44 (13%) patients developed hyperkalemia associated with sulfamethoxazole/trimethoprim use for over 49 (interquartile range; 17-233) days. We found associations between the time to hyperkalemia development and sulfamethoxazole/trimethoprim dose (hazard ratio 1.238, 95% confidence interval 1.147-1.338, p < 0.001) and glucocorticoid use (hazard ratio 0.678, 95% confidence interval 0.524-0.877, p = 0.003). Interestingly, the Kaplan-Meier curves revealed that the concomitant use of glucocorticoids did not attenuate the risk of hyperkalemia in patients receiving high-dose sulfamethoxazole/trimethoprim (p = 0.747), whereas concomitant use of glucocorticoids significantly reduced the risk of hyperkalemia in patients receiving non-high dose sulfamethoxazole/trimethoprim (p < 0.001).

CONCLUSIONS

High-dose sulfamethoxazole/trimethoprim is a significant predictor of hyperkalemia. The effect of glucocorticoids on hyperkalemia varies depending on the sulfamethoxazole/trimethoprim dose.

Incidence of Co-Trimoxazole-Induced Hyperkalemia in a Tertiary Care Hospital

Background

Co-trimoxazole is a broad-spectrum antibiotic associated with hyperkalemia.

Objective

To determine the incidence of hyperkalemia and its risk factors in patients receiving co-trimoxazole.

Materials and Methods

A retrospective observational study involving all patients who received co-trimoxazole between 1 January 2012 and 1 January 2013 was conducted. Subjects were identified through a list generated from a computerized pharmacy system. The patients' demographic and clinical characteristics were retrieved from electronic medical records. Data were analyzed using univariate and multivariate logistic regression.

Results

One hundred sixty-one patients fulfilled the eligibility criteria. Of these, 46 (28.6%) experienced hyperkalemia. Around 35 (76%) of the patients who experienced hyperkalemia received co-administered medications that might induce hyperkalemia. The co-administration of co-trimoxazole with other medications that may induce hyperkalemia was found to be associated with higher incidence of hyperkalemia when compared to co-trimoxazole administration alone [adjusted OR 3.2, 95% CI (1.4-7.3), p=0.005]. Additionally, age > 60 years was associated with an increased risk of hyperkalemia when compared to younger age group 18-39 years [adjusted OR 6.5, 95% CI (2.1-19.7); p=0.001].

Conclusion

Co-trimoxazole use is associated with high incidence of hyperkalemia, especially among older patients and those receiving it in combination with other medications that might contribute to hyperkalemia development such as calcineurin inhibitors and β-blockers.

Co-trimoxazole induced hyperkalemia and potassium monitoring in hospitalized patients

Background Co-trimoxazole is an antibiotic combination used for the treatment of Pneumocystis jirovecii pneumonia, amongst others. Co-trimoxazole is known to increase serum potassium. For this reason, Dutch guidelines advise serum potassium monitoring in high-risk patients. Objective This study aimed to determine average serum potassium rise after administration of intravenous co-trimoxazole in hospitalized patients, compared to intravenous ceftriaxone. This study also aimed to determine adherence to Dutch guidelines by measuring the incidence of serum potassium monitoring in these patients. Setting Data was collected retrospectively from patients in five departments of the Canisius Wilhelmina Hospital, a teaching hospital in Nijmegen, the Netherlands. Method Data was collected and compared from patients that received intravenous co-trimoxazole (n = 66) and intravenous ceftriaxone (n = 132) in the period of November 2008-November 2017. For each patient using co-trimoxazole, two patients using ceftriaxone were included in a paired fashion. Baseline and follow-up potassium were collected, if available. Additionally, it was tested if serum potassium was measured around the initiation of antibiotic therapy. Main outcome measure Changes in serum potassium where obtainable in 30 patients using cotrimoxazole and 40 patients using ceftriaxone. When compared to ceftriaxone, administration of intravenous co-trimoxazole was associated with a significant mean increase in serum potassium (+0.55 mmol/l, 95% CI 0.29-0.80, p < 0.001). After correction for confounders (baseline potassium, estimated glomerular filtration rate 30 ≤ 60, the presence of haematological malignancies and the usage of corticosteroids), this effect shrunk noticeably, but remained significant (+0.28 mmol/l, 95% CI 0.03-0.53, p = 0.031). Results The incidence of hyperkalemia at follow-up was 20% in the cotrimoxazole group, compared to 5% in the ceftriaxone group. Despite this, serum potassium was often not measured in patients using intravenous cotrimoxazole, being 76% at baseline and 55% in the period of 48-120 h after antibiotic therapy initiation, compared to 87% and 34% in the ceftriaxone group respectively. Conclusion Adherence to Dutch guidelines was poor as serum potassium monitoring was often not performed. As intravenous co-trimoxazole usage is associated with a significant increase in mean serum potassium, monitoring is strongly recommended.

Co-trimoxazole induced hyperkalemia and potassium monitoring in hospitalized patients

Background Co-trimoxazole is an antibiotic combination used for the treatment of Pneumocystis jirovecii pneumonia, amongst others. Co-trimoxazole is known to increase serum potassium. For this reason, Dutch guidelines advise serum potassium monitoring in high-risk patients. Objective This study aimed to determine average serum potassium rise after administration of intravenous co-trimoxazole in hospitalized patients, compared to intravenous ceftriaxone. This study also aimed to determine adherence to Dutch guidelines by measuring the incidence of serum potassium monitoring in these patients. Setting Five departments of the Canisius Wilhelmina Hospital, a teaching hospital in Nijmegen, the Netherlands. Method Data was collected and compared from patients that received intravenous co-trimoxazole (n = 66) and intravenous ceftriaxone (n = 132) in the period of November 2008–November 2017. For each patient using co-trimoxazole, two patients using ceftriaxone were included in a paired fashion. Baseline and follow-up potassium were collected, if available. Additionally, it was tested if serum potassium was measured around the initiation of antibiotic therapy. Main outcome measure Changes in serum potassium where obtainable in 30 patients using cotrimoxazole and 40 patients using ceftriaxone. When compared to ceftriaxone, administration of intravenous co-trimoxazole was associated with a significant mean increase in serum potassium (+ 0.55 mmol/l, 95% CI 0.29–0.80, p < 0.001). After correction for confounders (baseline potassium, estimated glomerular filtration rate 30 to < 60, the presence of haematological malignancies and the usage of corticosteroids), this effect shrunk noticeably, but remained significant (+ 0.28 mmol/l, 95% CI 0.03–0.53, p = 0.031). Results The incidence of hyperkalemia at follow-up was 20% in the cotrimoxazole group, compared to 5% in the ceftriaxone group. Despite this, serum potassium was often not measured in patients using intravenous cotrimoxazole, being 76% at baseline and 55% in the period of 48–120 h after antibiotic therapy initiation, compared to 87% and 34% in the ceftriaxone group respectively. Conclusion Adherence to Dutch guidelines was poor as serum potassium monitoring was often not performed. As intravenous co-trimoxazole usage is associated with a significant increase in mean serum potassium, monitoring is strongly recommended.

American Geriatrics Society 2019 Updated AGS Beers Criteria® for Potentially Inappropriate Medication Use in Older Adults

The American Geriatrics Society (AGS) Beers Criteria® (AGS Beers Criteria®) for Potentially Inappropriate Medication (PIM) Use in Older Adults are widely used by clinicians, educators, researchers, healthcare administrators, and regulators. Since 2011, the AGS has been the steward of the criteria and has produced updates on a 3-year cycle. The AGS Beers Criteria® is an explicit list of PIMs that are typically best avoided by older adults in most circumstances or under specific situations, such as in certain diseases or conditions. For the 2019 update, an interdisciplinary expert panel reviewed the evidence published since the last update (2015) to determine if new criteria should be added or if existing criteria should be removed or undergo changes to their recommendation, rationale, level of evidence, or strength of recommendation. J Am Geriatr Soc 67:674-694, 2019.

Trimethoprim use for urinary tract infection and risk of adverse outcomes in older patients: cohort study

OBJECTIVE

To determine if trimethoprim use for urinary tract infection (UTI) is associated with an increased risk of acute kidney injury, hyperkalaemia, or sudden death in the general population.

DESIGN

Cohort study.

SETTING

UK electronic primary care records from practices contributing to the Clinical Practice Research Datalink linked to the Hospital Episode Statistics database.

PARTICIPANTS

Adults aged 65 and over with a prescription for trimethoprim, amoxicillin, cefalexin, ciprofloxacin, or nitrofurantoin prescribed up to three days after a primary care diagnosis of UTI between April 1997 and September 2015.

MAIN OUTCOME MEASURES

The outcomes were acute kidney injury, hyperkalaemia, and death within 14 days of a UTI treated with antibiotics.

RESULTS

Among a cohort of 1 191 905 patients aged 65 and over, 178 238 individuals were identified with at least one UTI treated with antibiotics, comprising a total of 422 514 episodes of UTIs treated with antibiotics. The odds of acute kidney injury in the 14 days following antibiotic initiation were higher following trimethoprim (adjusted odds ratio 1.72, 95% confidence interval 1.31 to 2.24) and ciprofloxacin (1.48, 1.03 to 2.13) compared with amoxicillin. The odds of hyperkalaemia in the 14 days following antibiotic initiation were only higher following trimethoprim (2.27, 1.49 to 3.45) compared with amoxicillin. However, the odds of death within the 14 days following antibiotic initiation were not higher with trimethoprim than with amoxicillin: in the whole population the adjusted odds ratio was 0.90 (95% confidence interval 0.76 to 1.07) while among users of renin-angiotensin system blockers the odds of death within 14 days of antibiotic initiation was 1.12 (0.80 to 1.57). The results suggest that, for 1000 UTIs treated with antibiotics among people 65 and over, treatment with trimethoprim instead of amoxicillin would result in one to two additional cases of hyperkalaemia and two admissions with acute kidney injury, regardless of renin-angiotensin system blockade. However, for people taking renin-angiotensin system blockers and spironolactone treatment with trimethoprim instead of amoxicillin there were 18 additional cases of hyperkalaemia and 11 admissions with acute kidney injury.

CONCLUSION

Trimethoprim is associated with a greater risk of acute kidney injury and hyperkalaemia compared with other antibiotics used to treat UTIs, but not a greater risk of death. The relative risk increase is similar across population groups, but the higher baseline risk among those taking renin-angiotensin system blockers and potassium-sparing diuretics translates into higher absolute risks of acute kidney injury and hyperkalaemia in these groups.

The effect of co-trimoxazole on serum potassium concentration: safety evaluation of a randomized controlled trial

AIMS

Co-trimoxazole maintains a well-established role in the treatment of Pneumocystis jirovecii and Toxoplasma gondii, as well as urinary tract infections. Observational studies report hyperkalaemia to be associated with co-trimoxazole, which may stem from an amiloride-like potassium-sparing effect. The current study investigated changes in serum potassium in patients without acute infections, and the influence of concomitant antikaliuretic drugs on this effect.

METHODS

A post hoc analysis was carried out of a randomized controlled trial in patients with interstitial lung disease who were assigned to placebo or 960 mg co-trimoxazole twice daily. Serum potassium and creatinine were measured at baseline, 6 weeks, and 6, 9 and 12 months. The primary outcome was the difference in mean serum potassium concentrations between co-trimoxazole and placebo at 6 weeks.

RESULTS

Mean serum potassium levels were similar at baseline: 4.24 (± 0.44) mmol l^-1 in the 87 co-trimoxazole group participants and 4.25 (± 0.39) mmol l^-1 in the 83 control participants. Co-trimoxazole significantly increased mean serum potassium levels at 6 weeks, with a difference between means compared with placebo of 0.21 mmol l^-1 [95% confidence interval (CI) 0.09, 0.34; P = 0.001). This significant increase in serum potassium was detectable even after exclusion of patients on antikaliuretic drugs, with a difference between means for co-trimoxazole compared with placebo of 0.23 mmol l^-1 (95% CI 0.09, 0.38; P = 0.002). There were 5/87 (5.7%) patients on co-trimoxazole whose serum potassium concentrations reached ≥5.5 mmol l^-1 during the study period.

CONCLUSIONS

Co-trimoxazole significantly increases serum potassium concentration, even in participants not using antikaliuretic drugs. While the magnitude of increase was often minor, a small proportion in our outpatient cohort developed hyperkalaemia of clinical importance.